全文获取类型
收费全文 | 22942篇 |
免费 | 189篇 |
国内免费 | 130篇 |
专业分类
测绘学 | 354篇 |
大气科学 | 1203篇 |
地球物理 | 4354篇 |
地质学 | 8987篇 |
海洋学 | 2230篇 |
天文学 | 5266篇 |
综合类 | 42篇 |
自然地理 | 825篇 |
出版年
2022年 | 263篇 |
2021年 | 431篇 |
2020年 | 394篇 |
2019年 | 461篇 |
2018年 | 939篇 |
2017年 | 864篇 |
2016年 | 879篇 |
2015年 | 365篇 |
2014年 | 765篇 |
2013年 | 1287篇 |
2012年 | 897篇 |
2011年 | 1089篇 |
2010年 | 1054篇 |
2009年 | 1212篇 |
2008年 | 1038篇 |
2007年 | 1217篇 |
2006年 | 1060篇 |
2005年 | 565篇 |
2004年 | 533篇 |
2003年 | 539篇 |
2002年 | 559篇 |
2001年 | 508篇 |
2000年 | 409篇 |
1999年 | 333篇 |
1998年 | 322篇 |
1997年 | 328篇 |
1996年 | 254篇 |
1995年 | 261篇 |
1994年 | 236篇 |
1993年 | 182篇 |
1992年 | 208篇 |
1991年 | 181篇 |
1990年 | 195篇 |
1989年 | 187篇 |
1988年 | 156篇 |
1987年 | 182篇 |
1986年 | 170篇 |
1985年 | 205篇 |
1984年 | 198篇 |
1983年 | 197篇 |
1982年 | 188篇 |
1981年 | 172篇 |
1980年 | 162篇 |
1979年 | 182篇 |
1978年 | 158篇 |
1977年 | 142篇 |
1976年 | 133篇 |
1975年 | 136篇 |
1974年 | 125篇 |
1973年 | 165篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
E.?S.?KazakEmail author E.?G.?Kalitina N.?A.?Kharitonova G.?A.?Chelnokov E.?V.?Elovskii I.?V.?Bragin 《Moscow University Geology Bulletin》2018,73(3):287-294
This paper reports the results of the experimental determination of the coefficient of sorption of rare-earth elements and yttrium (REY) under conditions of acidic pH using several strains of heterotrophic bacteria (Microbacterium sp., Curtobacterium sp., Bacillus subtilis, Pseudomonas putida, and Bacillus pumilis) that are widespread in natural and technogenic waters of the Far East (Russia). Insignificant fractionation between heavy and light rare-earth elements, negative cerium and dysprosium anomalies, and a positive europium anomaly were revealed. The selectivity of REY biosorption by gram-positive and gram-negative bacteria, as well as inertia of the biosorption process under more acidic conditions of the medium, were shown. 相似文献
32.
The population and distribution of carbon-oxidizing and sulfate-reducing bacteria in the soils of the Mozhaisk Reservoir are studied. 相似文献
33.
Sources of dissolved REE in mountainous streams draining granitic rocks, Sierras Pampeanas (Córdoba, Argentina) 总被引:1,自引:0,他引:1
M. Gabriela García Karina L. Lecomte Andrea I. Pasquini Stella M. Formica Pedro J. Depetris 《Geochimica et cosmochimica acta》2007,71(22):5355-5368
Stream waters draining granitic terrains from the highest part (850 to 2200 m a.s.l.) of Sierras Pampeanas (Córdoba, Argentina, ∼32°S, ∼65°W) were sampled in order to define sources and distribution of dissolved rare earth elements (REE), and to describe the geochemical processes that govern their mobility. The contribution of the regional granite to the dissolved REE pool in stream water is limited due to the physical conditions predominating in the area (i.e., steep slopes and semiarid climate). Therefore, precipitation is considered a seasonally significant source controlling REE concentration in stream water. Dissolved REE concentrations are inversely correlated with monthly precipitation and rainfall frequency. During the rainy season (i.e., the austral summer) REE concentrations in stream water are lower than during the dry season (i.e., austral winter). Such low concentrations reflect the balance between the REE input from precipitation and their removal by adsorption. In contrast, during the dry season, the longer residence time of water within fractures and colluvium determines an increased REE concentration in the base flow. Lower pH values also contribute to raise REE concentration through desorption from mineral surfaces. 相似文献
34.
35.
N. V. Makarova V. M. Makeev T. V. Sukhanova P. S. Miklyaev A. L. Dorozhko I. V. Korobova 《Moscow University Geology Bulletin》2012,67(4):209-217
The neotectonic structures of the Lower Oka (Nizhneokskii) Region formed under different geodynamic conditions. This is attested by the morphology, orientation, internal structure, and jointing of the structures. The Oka-Tsna arc formed under the effect of tension from an inner source on the one hand and stress from the Alpian belt on the other hand. The latitudinally-oriented structures of the northwestern slope of the Tokmovo arc emerged as a result of uplift and widening. Both types of structure are combined within the limits of the Oka-Murom trough, which is a geodynamically active zone. 相似文献
36.
37.
Spectrum–Röntgen–Gamma (SRG) is a space observatory designed to observe astrophysical objects in the X-ray range of the electromagnetic spectrum. SRG is planned to be launched in 2019 by a Proton-M launch vehicle with a DM3 upper stage. The spacecraft will be delivered to an orbit around the Sun–Earth collinear libration point L2 located at a distance of ~1.5 million km from the Earth. Although the SRG launch scheme has already been determined at present, in this paper we consider an alternative spacecraft transfer scenario using a lunar gravity-assist maneuver. The proposed scenario allows a oneimpulse transfer from a low Earth orbit to a small-amplitude orbit around the libration point to be performed while fulfilling the technical constraints and the scientific requirements of the mission. 相似文献
38.
K. Giannopoulou M. Santamouris I. Livada C. Georgakis Y. Caouris 《Pure and Applied Geophysics》2010,167(11):1433-1449
The present paper investigates the impact of canyon geometry on the temperature regime and nocturnal heat island development
in the very dense urban area of Athens, Greece. Detailed measurements of air temperature have been carried out within three
deep urban canyons of different aspect ratios (H/W = 3, 2.1 and 1.7) during the night period of the summer and autumn of 2007. An analysis was carried out to investigate the
relative impact of the canyon geometry, the undisturbed wind velocity, ambient temperature, and cloud cover on the development
of a nocturnal heat island. A clear increase of the median, maximum and minimum values of the cooling rates has been observed
for decreasing aspect ratios. Under low ambient temperatures, high wind speeds correspond to a substantial rise of the cooling
rate in the urban canyons mainly because of the increased convective losses. On the contrary, cooling rates decrease substantially
under high-undisturbed wind speeds and ambient temperatures because of the important convective gains. The impact of cloud
cover was found to be important as cloudy skies cause a substantial decrease of the cooling rates in the urban canyons. Comparisons
were performed between the temperature data collected in the three studied urban canyons and temperatures recorded in an urban
as well as a suburban open space station. 相似文献
39.
A model is proposed that shows the relation of the block structure of the crust and earthquake sources (Sadovskii, 1979; Rodionov, 1979, 1984, 1994; Bugaev, 1999, 2011, 2014, 2015). The model can formalize how to assess the prediction of seismic regime parameters depending on the elastic limit and conditions and rate of deformation of the Earth’s crust. The spent nuclear fuel repository site in Olkiluoto (Finland) and a site in the area of the Krasnoyarsk Mining and Chemical Combine are considered as examples. It is demonstrated that the parameters of the prediction graphs limit the location of the points of magnitude repeatability graphs calculated for a site based on samples of earthquakes in the area according to different authors. This makes it possible to recommend predictive assessment of seismic regime parameters for stability monitoring of the seismic regime and safety analysis of a geological environment’s insulation properties for waste sites from the results of seismological monitoring and high-precision observations of modern movements of the Earth’s crust. 相似文献
40.
Meysam Fadaee I. Anastasopoulos G. Gazetas M.K. Jafari M. Kamalian 《地震工程与工程振动(英文版)》2013,12(3):473-486
When seismic thrust faults emerge on the ground surface,they are particularly damaging to buildings,bridges and lifelines that lie on the rupture path.To protect a structure founded on a rigid raft,a thick diaphragm-type soil bentonite wall(SBW) is installed in front of and near the foundation,at sufficient depth to intercept the propagating fault rupture.Extensive numerical analyses,verified against reduced–scale(1 g) split box physical model tests,reveal that such a wall,thanks to its high deformability and low shear resistance,"absorbs" the compressive thrust of the fault and forces the rupture to deviate upwards along its length.As a consequence,the foundation is left essentially intact.The effectiveness of SBW is demonstrated to depend on the exact location of the emerging fault and the magnitude of the fault offset.When the latter is large,the unprotected foundation experiences intolerable rigid-body rotation even if the foundation structural distress is not substantial. 相似文献